The present invention relates to novel azabicyclic compounds, methods for preparing same, and intermediates, and particularly to compounds having the following formula: ##STR1## wherein: A is a member selected from the group consisting of ##STR2## R.sub.1 is a member selected from the group consisting of loweralkyl, phenyl, substituted phenyl, phenyl lower alkyl, substituted phenyl lower alkyl, loweralkylamido phenyl, and heterocyclic aryl;
R.sub.2 -r.sub.5 are each members selected from the group consisting of hydrogen, halo, cyano, COOR', CONR'R", CH.sub.2 NR'R", OR'", loweralkyl, phenyl, substituted phenyl, phenyl loweralkyl, and substituted phenyl loweralkyl, said R' and R" each being a member selected from the group consisting of hydrogen and loweralkyl and said R'" being a member selected from the group consisting of hydrogen, loweralkyl, phenyl, and substituted phenyl;
R.sub.6 is a member selected from the group consisting of loweralkyl, phenyl, and substituted phenyl; and
R.sub.7 and R.sub.8 are each members selected from the group consisting of hydrogen, halo, loweralkyl, loweralkoxy, and amino.
As used herein, the terms "loweralkyl" and "loweralkoxy" mean straight or branched chain aliphatic hydrocarbons of from 1 to about 6 carbon atoms such as, for example, methyl, ethyl, isopropyl, pentyl, and the like loweralkyls, and, respectively, methoxy, ethoxy, isopropoxy, pentoxy, and the like loweralkoxys. The term "halo" includes fluoro, bromo, chloro, and iodo. The term "substituted phenyl" means phenyl substituted with from 1 to 3 members each selected from the group consisting of loweralkyl, loweralkoxy, halo, and amino.
Heterocyclic aryl groups comprise five- to ten-membered heteroaromatics wherein the hetero atoms are one or more sulfur, nitrogen, or oxygen atoms. Included are monocyclic heteroaryls comprising five to six members having at least one sulfur, nitrogen or oxygen atom as the heteroatom, and bicyclic heteroaryls having up to ten members and having, as one of the cyclic moieties, a five to six membered heteroaromatic ring with at least one sulfur, nitrogen or oxygen atom as the heteroatom. Specific examples of such groups are pyridyl, quinolyl, imidazolyl, pyrazinyl, pyrrolyl, thienyl, thiazolyl, thiadiazolyl, pyrazolyl, triazolyl, oxazolyl and pyrimidinyl. The azaheterocyclic aryls may, if so desired, be further substituted at the ring carbon and nitrogen atoms. For example, the heterocyclic moiety may be substituted with a lower alkyl, e.g., 6-methyl-2-pyridyl, 4-ethyl-2-pyrimidyl, and the like; or, for example, a 2-pyrrolyl moiety may be alkylated to the corresponding N-alkyl-2-pyrrolyl. Further, the carbon heterocyclic aryl linkage may be at any one of the several carbon atoms of the heterocycle as, for example, at the 2-,3-, or 4-position of the pyridyl moiety.
The compounds of formula (I) wherein A is ##STR3## may be prepared by reacting a pyridone of formula (II) with a suitable phthalazinedione of formula (III) in a suitable inert organic solvent, as for example, acetone, acetonitrile, dichloromethane, chloroform, or the like. The solvent must be inert to the reactants and must remain a liquid at the temperature of the reaction. The reaction may be conducted at temperatures up to ambient, but cooling is preferred. Best results have been obtained at about -60.degree. C. The pyridone is preferably employed in excess. The reaction is usually completed after about 2 hours, at which time the intermediate of formula (IV) may be isolated by conventional techniques or may be used without isolation. This intermediate is then reduced by conventional hydrogenation techniques to yield the desired product of formula (I). This reaction may be conducted in a lower alkanol, such as methanol, ethanol, and the like; ethyl acetate; methylene chloride; mixtures thereof; and the like as solvent. A preferred solvent is a mixture of dichloromethane and methanol. Any hydrogenation catalyst may be used, such as a platinium or palladium catalyst, e.g. Pd/C, Pd/BaSO.sub.4, Pd/CaCO.sub.3, or the like. Hydrogen pressure may be atmospheric or greater. Removal of the catalyst by filtration or the like, concentration of the filtrate, and isolation and purification of the resulting product of conventional means yields the compound of formula (I). This reaction scheme may be illustrated by the following, wherein R.sub.1 -R.sub.8 are as previously defined, R'.sub.1 is a member selected from the group consisting of loweralkyl, phenyl, substituted phenyl, phenyl loweralkyl, substituted phenyl loweralkyl, nitrophenyl, and heterocyclic aryl, and R.sub.7 ' and R.sub.8 ' are each members selected from the group consisting of hydrogen, halo, loweralkyl, loweralkoxy, amino, and nitro: ##STR4##
The compounds of formula (I) where A is ##STR5## may be prepared by the same procedure, substituting a suitable 4-substituted urazole of formula (V) for the phthalazinedione of formula (III) used above. The same solvent and temperature conditions may be employed in this reaction as in the above-described reaction, but preferably equivalent amounts of the two reactants are employed. Best results have been obtained at about 0.degree. C. This reaction scheme may be illustrated by the following, wherein R.sub.1 -R.sub.6 and R'.sub.1 are as previously defined: ##STR6##
Compounds of formula (I) wherein R.sub.1 is azaheterocyclic aryl may be converted to the corresponding pharmaceutically acceptable quaternary salts by reaction with a suitable quaternizing agent, e.g., lower alkyl iodides such as methyl iodide and the like. These quaternary salts are considered part of the present invention.
The starting materials of formulas (III) and (V) are known or may be prepared by known techniques described in, for example, J. Amer. Chem. Soc., 84,966(1962); J. Thiele and O. Stange, Ann., 283, 1(1849); G. Zinner and W. Denker, Arch. Pharm., 294, 370(1961); and J. C. Stickler and W. H. Pirkle, J. Org. Chem., 31, 3445(1961). The pyridones of formula (II) are generally known. See, for example, "The Chemistry of Heterocyclic Compounds-Pyridine and its Derivatives," Volume 14 Supplement part 3, R. Abramovich, Editor, pages 597-1180, J. Wiley & Sons.
Compounds of formula (I) have central nervous system modifying activity, particularly as depressants, and are therefore useful as tranquilizers. The preferred dosage level is from about 30 mg/kg to about 300 mg/kg. In addition, they have cardiovascular activity and are thus useful in the treatment of bradycardia and as cardiotonic agents. For use as cardiovascular agents, the compounds are preferably administered at dosage levels ranging from about 50 mg/kg to about 100 mg/kg.
The compounds of formulas (IV) and (VI) are novel and are useful as intermediates in the preparation of compounds of formula (I). These novel intermediates are also considered to be part of the present invention and may be represented by the following general formula: ##STR7## wherein A' is a member selected from the group consisting of ##STR8##
The methods described whereby the compounds of formula (I) are prepared are novel and are thus also considered to be part of the present invention.
The preferred compounds of formula (I) of the invention are those wherein R.sub.2 -R.sub.5 are hydrogen, R.sub.6 is a member selected from the group consisting of phenyl and substituted phenyl, and R.sub.7 and R.sub.8 are hydrogen. The more preferred compounds of the invention are those wherein A is ##STR9## R.sub.2 -R.sub.5 are hydrogen, and R.sub.6 is phenyl. The most preferred compounds of the invention are those wherein A is ##STR10## R.sub.2, R.sub.3 and R.sub.5 are hydrogen; R.sub.4 is a member selected from the group consisting of hydrogen and loweralkyl, R.sub.6 is phenyl, and R.sub.1 is a member selected from the group consisting of phenyl, substituted phenyl, and phenyl alkyl.
The present invention is illustrated by the following examples: